Battery management systems for energy storage devices

Abstract

Disclosed herein are methods and systems for monitoring and/or regulating energy storage devices. Examples of such monitoring and/or regulating include cell balancing, dynamic impedance control, breach detection and determination of state of charge of energy storage devices.

1 . A method for regulating an energy storage device comprising at least one electrochemical cell comprising a negative electrode, positive electrode and an electrolyte between said negative and positive electrodes, the method comprising:
 (a) measuring, with the aid of a temperature sensor in thermal communication with said electrochemical cell, an operating temperature of the electrochemical cell, wherein at least one of said negative electrode, positive electrode and electrolyte are in a liquid state at said operating temperature;   (b) calculating, with the aid of a battery management system, an impedance of a current flow path leading through said electrochemical cell using a correspondence between impedance and temperature stored in a memory location of said battery management system; and   (c) calculating, with the aid of said battery management system, a state of charge of said electrochemical cell using said impedance calculated in (b) and a current measured through said electrochemical cell.   
     
     
         2 . The method of  claim 1 , wherein said electrochemical cell is among a plurality of electrochemical cells of said energy storage device, and wherein, subsequent to (c), the state of charge of the electrochemical cell is balanced against the state of charge of other cells of said plurality of electrochemical cells. 
     
     
         3 .- 7 . (canceled) 
     
     
         8 . The method of  claim 1 , wherein said positive electrode comprises one or more of zinc, cadmium, mercury, tin, lead, bismuth, antimony, tellurium and selenium. 
     
     
         9 . The method of  claim 1 , wherein said operating temperature is at least about 200° C. 
     
     
         10 .- 11 . (canceled) 
     
     
         12 . A method for detecting a breach of an electrochemical cell, the method comprising:
 (a) providing an electrochemical cell comprising a negative electrode, an electrolyte and a positive electrode, wherein at least one of the negative electrode, the electrolyte and the positive electrode is in a liquid state at an operating temperature of the electrochemical cell that is at least about 250° C., and wherein a seal isolates the negative electrode, the electrolyte and the positive electrode from an environment external to the electrochemical cell;   (b) monitoring the electrochemical cell for an electrical signature that is indicative of a breach of the seal and exposure of at least one of the positive electrode, the electrolyte, and the negative electrode to the environment; and   (c) in response to the electrical signature, inactivating the electrochemical cell, cooling the electrochemical cell, discharging the electrochemical cell and/or notifying a system operator.   
     
     
         13 .- 14 . (canceled) 
     
     
         15 . The method of  claim 12 , wherein the electrochemical cell is one of a plurality of electrochemical cells connected in parallel and/or series and at least a portion of the plurality of electrochemical cells are inactivated, cooled and/or discharged in response to the electrical signature. 
     
     
         16 .- 20 . (canceled) 
     
     
         21 . The method of  claim 12 , wherein the electrical signature corresponds to (i) a leakage current that is increased relative to a baseline leakage current associated with an unbreached cell, (ii) a self-discharge rate of the electrochemical cell that is increased relative to a baseline self-discharge rate associated with an unbreached cell, (iii) a charge/discharge Coulombic efficiency value that is decreasing over time and/or is below a baseline Coulombic efficiency value associated with an unbreached cell or an unbreached group of cells, or (iv) a voltage during charging or discharging of the electrochemical cell that is decreased relative to a baseline charge/discharge voltage associated with an unbreached cell. 
     
     
         22 .- 25 . (canceled) 
     
     
         26 . The method of  claim 12 , wherein the electrical signature is further indicative of the negative electrode shorting with the positive electrode. 
     
     
         27 .- 30 . (canceled) 
     
     
         31 . The method of  claim 12 , wherein the operating temperature is between about 250° C. and 750° C. 
     
     
         32 . The method of  claim 12 , wherein (b) and (c) are performed using a computer processor that is programmed to (i) monitor the electrochemical cell for the electrical signature and (ii) initiate the inactivation, cooling and/or discharging of the electrochemical cell. 
     
     
         33 .- 91 . (canceled) 
     
     
         92 . A system for energy storage, comprising:
 an energy storage device comprising a plurality of electrochemical cells, wherein each of the plurality of electrochemical cells comprises a negative electrode, a positive electrode and an electrolyte between the negative and positive electrodes, wherein at least one of the negative electrode, the electrolyte and the positive electrode is in a liquid state at an operating temperature of a respective one of the plurality of electrochemical cells that is at least about 250° C.; and   at least one controller in electrical communication with the energy storage device, wherein the at least one controller is programmed to (a) monitor an operating state of the energy storage device, which operating state of the energy storage device includes an operating state of an individual electrochemical cell of the plurality of electrochemical cells, and (b) control the energy storage device in response to monitoring the operating state of the energy storage device to enable cell balancing between at least a subset of the plurality of electrochemical cells.   
     
     
         93 . The system of  claim 92 , wherein the energy storage device stores and returns electrical energy to an electric power grid. 
     
     
         94 . The system of  claim 92 , wherein the controller receives power from an auxiliary power source that includes one or more of an electric power grid and a back-up battery system. 
     
     
         95 .- 96 . (canceled) 
     
     
         97 . The system of  claim 92 , wherein the controller is configured to (i) slow or stop a charging rate of the energy storage device when a pre-defined maximum voltage cut-off limit is reached, (ii) slow or stop a discharging rate of the energy storage device when a pre-defined minimum voltage cut-off limit is reached, (iii) slow or stop a charging or discharging rate of the energy storage device when a pre-defined temperature limit is exceeded, (iv) open relays or contactors in response to a measured current that exceeds a pre-determined value during charging, discharging or idling, or (v) start, stop or pause operation or alter an operational parameter of the energy storage device in response to a signal received from a higher order controller or from a remotely located control station. 
     
     
         98 .- 119 . (canceled) 
     
     
         120 . The system of  claim 92 , wherein the system restricts access to different layers of system functionality based on authentication of a user. 
     
     
         121 . (canceled) 
     
     
         122 . The system of  claim 92 , wherein the at least one controller balances state of charge (SOC) of individual electrochemical cells or groups of electrochemical cells of the plurality of electrochemical cells by selectively charging one or more electrochemical cells with lower SOC from an external power source tied to an electric power grid or from an isolated external power supply. 
     
     
         123 . (canceled) 
     
     
         124 . The system of  claim 92 , wherein the at least one controller balances state of charge (SOC) of individual electrochemical cells or groups of electrochemical cells of the plurality of electrochemical cells by bypassing charging current around one or more electrochemical cells that are at full SOC, thereby providing the bypassed charging current to one or more electrochemical cells that are SOC deficient. 
     
     
         125 .- 127 . (canceled) 
     
     
         128 . The system of  claim 92 ,
 wherein the operating state of the energy storage device includes the operating temperature and a voltage of the individual electrochemical cell, and wherein the at least one controller is programmed such that if the operating temperature of the individual electrochemical cell is at least 50° C. less than a predetermined operating temperature of the energy storage device, the controller does not use the voltage to control the energy storage device.   
     
     
         129 . (canceled) 
     
     
         130 . The system of  claim 128 , wherein the predetermined operating temperature of the energy storage device is at least about 250° C. 
     
     
         131 . The system of  claim 92 , wherein the at least one controller is programmed to (i) monitor a first parameter that is indicative of the operating state of the individual electrochemical cell, (ii) determine a second parameter of the individual electrochemical cell based on the first parameter, and (iii) in response to the second parameter, control the operating state of the individual electrochemical cell. 
     
     
         132 . The system of  claim 131 , wherein (i) the first parameter is voltage, and the controller monitors the individual electrochemical cell through voltage sensing, or (ii) the first parameter is current, and the controller monitors the individual electrochemical cell through current sensing. 
     
     
         133 . The system of  claim 131 , wherein the second parameter is state of charge (SOC) or state of health (SOH).